#!/bin/ksh
# A wrapper for SpamAssassin suitable for calling from a dot-qmail file
# Version: 1.5
#
# Usage:
#  |ifspamh mail-address
#
# Mail will be reinjected to the given mail-address, with annotatations
# if SpamAssassin thinks that it is a likely spam message.
#
# For example, in your .qmail file:
#    |ifspamh <user>-isspam
#    ./Mailbox
# (or however you want to deliver the mail if it isn't a spam message)
#
# This will forward anything that SpamAssassin deems spam to the 
# given address.
#
# in your .qmail-isspam file:
#    ./Mail/isspam
# (or wherever you want to save the Spam mail)
#
# For more details on SpamAssassin, how to set preferences, whitelists,
# etc, see 'Mail::SpamAssassin::Conf(3)' - and put the preferences
# in ~/.spamassassin/user_prefs
#
# For more detail on .qmail files, see dot-qmail(5) and qmail-command(8)
# 
# Author: James R Grinter
# jrg@watching.org 24/03/2002
# Last Update: 28/02/2003
# URL: http://www.gbnet.net/~jrg/qmail/ifspamh/
#
# Requires: spamc, spamd, qmail and 822field (from DJB's mess822 package)
# to be installed and working.
#
# Also requires your /bin/sh to have a "printf" available
# (most do, if yours doesn't then consider fetching ksh-93
# from http://www.research.att.com/sw/download/, or using bash)
#
# N.B.
# If you are using vpopmail, make sure you are using at least
# version 5.3.6.
#
# If you want to run SpamAssassin globally for every email, see the
# qmail-spamc/qmail-scanner approach in the qmail/ subdirectory of the
# SpamAssassin distribution
#

# spamc - client location
SPAMC=/usr/local/bin/spamc
# qmail's forward program location
FORWARDBIN=/var/qmail/bin/forward
# mess822 822field location
M822FIELD=/usr/local/bin/822field

#################################################################
# nothing beyond here should require adjustment
#################################################################

FORWARD="$1"

if [ -z "$FORWARD" ]; then
  echo "Usage: ifspamh [address]"
  exit 111
fi

# we used to skip 'From ' - the 1st line that got added by spamd/spamc
# but it seems newer versions don't add it (and SA 2.50 adds a 3 line 
# Received header)
output="`$SPAMC | sed '1{/^From .*/d;}'`"
exitcode=$?

# spamc will not process a "large email"
msize=`echo "$output" | wc -c`
# there's also a sizelimit with some shells that triggers around the 512kB mark
# with an external printf and arguments size so we stop at this point
if [ $msize -gt 250000 ]; then
  # probably deemed too large anyway .. let it through
  exit 0
fi

flagvalue=`printf "%s\n" "$output" | $M822FIELD X-Spam-Flag | sed 's/^ //'`
# X-Spam-Flag might contain "YES"

if [ "$flagvalue" = "YES" ]; then
  # match - likely spam
  # no match - not a spam
  # forward on the email
  printf "%s\n" "$output" | $FORWARDBIN $FORWARD
  if [ $? -eq 0 ]; then
    # so qmail will not do any further deliveries in .qmail file
    exit 99
  fi
  # problem calling inject - temp failure
  exit 111
else
  # spamc doesn't distinguish temporary failure 
  # if we're passing through the message
  # so look for signs that spamd provided the output..
  flag2value=`printf "%s\n" "$output" | $M822FIELD X-Spam-Status`
  exitcode2=$?
  if [ $exitcode2 -ne 0 ]; then
    # X-Spam-Status header not present in message -> failure of spamc/spamd?
    # spamc will not process a "large email", but this is accounted for above
    # so indicate temporary failure
    echo "spamc returned temporary failure"
    exit 111
  fi

  # indicate that qmail should continue processing dot-qmail file
  exit 0
fi